Telephone system.



A. H. DYSON.

TELEPHONE SYSTEM. APPLI-OATION FILED APR.11, 1902.

1002240 S- Patented Sept.`5,1911,

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ALFRED I-I. .DYSON, 0F CHICAGO, ILLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTS, TO STROMBERG-CARLSON TELEPHONE MANUFACTURING COMPANY, OF ROCHESTER, NEW YORK, A CORPORATION OF NEW YORK.

TELEPHONE SYSTEM.

To al?, whom it may concern.'

Be it known that I, ALFRED H. DYSON, a citizen of the United States of America, and resident of Chicago, Cook county, Illinois, have invented a certain new and useful Improvement in Telephone Systems, of which the following is a specification. I

My invention relates to telephone systems in which the circuits are of such character that any subscriber of one exchange may converse with any subscriber of another exchange. Telephone circuits of this character are usually known as trunking systems, the connection between the two exchanges consisting of a number of lines known as trunk lines. With this arrangement, a subscriber of one exchange can send in a call, asking for connection with a subscriber of another exchange, and the originating operator, or operator receiving the call, can then signal the trunking operator of the second exchange, so as to ascertain what trunking line can be employed between the two exchanges. If the called subscriber is not busy, the trunking operator at the second exchange then instructs the originating operator to connect up with a certain trunk line, and at the same time connects this line with the line of the called subscriber. In a system of this character,

it is desirable that the originating operator have complete supervision of the connections--that is to say, that suitable signals be provided whereby this operator may not only know when the calling subscriber has signaled for disconnection, but may also know when the called subscriber has finished talking and signaled for like disconnection. It is also desirable that suitable circuits and signal devices be provided for enabling the originating operator to signal the trunking operator to take down the connection. In view of certain approved methods of operation, it is also desirable in a system of this kind that current, both for talking and signaling purposes, be supplied from batteries located at the exchanges or central stations. In addition, line signals are provided which enable subscribers to signal the central operators, and the arrangements are preferably such that these line signals are restored or extinguished by the operators in answering calls. Systems thus operated are usually Specication of Letters Patent.

Application filed April 11, 1902.

Patented Sept. 5, 1911.

Serial No. 102,349.

known as common battery or central energy systems by reason of the current for all purposes being supplied from a common or central source.

Generally stated, it is one of the principal objects of my invention to provide a simple and eiiicient circuit arrangementwhereby trunking may be successfully carried on between two common battery or central energy exchanges.

A special object of my invention is to provide suitable devices and circuit arrangements whereby such trunking may be carried on between two exchanges characterized by certain methods of operation, and by signaling circuits of a certain character, as will hereinafter more fully appear.

Another object is to provide a simplified and improved arrangement of circuits and signals whereby the originating operator in a system of this character may have complete control and supervision of the connections.

In addition to these, it is also an object to provide certain details and features of improvement tending to increase the general eiiiciency and to render a system of this character in every way serviceable and satisfactory.

To the foregoing and other useful ends, my invention consists in matters hereinafter set forth and claimed.

The accompanying drawing is a diagram illustrating a trunking telephone system embodying the principles of my invention. In this diagram it will be observed that both the exchanges are of the common battery or central energy type, and that complete metallic line connections are employed, both for the trunk lines between the two exchanges, and also between the substations and their respective exchanges. It will be understood that only such devices and connections are shown as are necessary to a full understanding of the invention.

As thus illustrated, A represents substation apparatus of a common battery or central energy system, and B represents like substation apparatus. The substation A is, it will be seen, connected with the switchboard at the exchange or central station C. In a similar manner, the substation B is connected with a similar exchange D. The

two exchanges are illustrated as being connected by a trunk line E, which is employed for establishing connection between subscribers of the two exchanges, and also by means of what is known as an order circuitor line F, which latter is practically a private line between the two operators at the different exchanges. An induction connection X preferably connects the two parts of the order line. Now assuming that the subscriber at substation A desires connection with the subscriber at substation B, the operations and circuit connections which then take place are as follows: then the subscriber at substation A sends in a call by removing the receiver from the hookswitch, a line circuit is completed from the said switch 1 through the contact-point 2 and the primary 3 of the usual induction coil, thence over the limb or line conductor 4, through conductor 5, through the impe` dance or retardation coil 6, through the con` ductor 7 to the battery 8, thence through the conductor 9 and the retardation or impedance coil 10, through the conductor 11, through the coil 12 of the Aline relay, thence through the other limb or line conductor 13, and through the transmitter 14 to said hook-switch. This, it will be seen, energizes the line relay causing it to attract its arma ture. The said armature when attracted completes a local circuit from the batterv S, through the conductors 9 and 15, through the line lamp 1G, thence through contact- 17 and armat-ure 18, thence through the ground or common'connections 19 and 20 to said battery. The tlow of current through this local circuit causes the lamp 16 to glow. The central operator at the exchange indicated by C observing this signal, then inserts the answering plug in the spring jack connected with the calling subscribers line. One effect of thus placing the plug' in the jack is to short-circuit the coil of the line relay 12, thereby restoring or extinguishing the lamp 1G. This short-circuiting is secured by connecting the coil 21 of the supervisory relay allotted to the answering plug with both tip and ring contacts of the said plug. Consequently when the plug is inserted the line circuit includes the jack springs 22 and 23, the plug tip 24, the plug ring 25, and the said coil 21, rather than the coil 12 of the line relay. Thus the line relay is shunted out, the supervisory relay being of comparatively low resistance. The insertion of the plug in the jack in this manner also establishes connection between the substation and the operators talking set, and the subscriber then instructs the operator as to the character of the connection desired. Furthermore, the insertion of the plug in the jack of the calling subscriber establishes a short-local circuit from the battery 8 through conductor 26 and the coil 27 of the third or supplementary supervisory relay, thence through conductor 28 and the contact-point 29, through the listening key 30, through the sleeve-strand 31 ot the cord-circuit, through the plug-sleeve 32 of the answering plug, through the test-ing ring or sleeve contact 33 of the jack, thence through the conductors 34 and 5, and through the impedance coil 6 and conductor 7 to said battery. This energizes the said supervisory relay 27, causing the latter to attract its armature, so as to close the normally open switch-point in the circuits of the two supervisory lamps to be hereinafter described. Upon receiving the order from the calling subscriber, the originatng operator then presses the key 35, so as to establish connection between the talking sets of the two exchanges. The originating operator states to the trunking operator of exchange D that connection is desired with substation B; The trunking operator then assigns one of the many trunking line's usual between exchanges in a trunking circuit, which, in this case, itmay be assumed is the trunk line E. After thus assigning a line for use between the two exchanges, the trunking operator then tests the line ot substation B in any well known or approved way, and if the .line is not busy the plug of the trunking cord-circuit at exchange D is then inserted in the said jack connected with the line of substation B. The trunking operator then projects ringing' current onto the line, so as to ring the bell at substation B. The trunk line E having been assigned by the trunking operator for use between the two exchanges, the originating operator then inserts the calling plug of the cord-circuit at exchange C in the trunk jack, or jack connected with the trunk line. The insertion of the calling' plug in the trunk jack, in this manner, completes a cir cuit from the battery 8, through the armature 3G and contact-point 37, thence through the conductor 38, supervisory lamp 39, through the conductor 40 and contact-point 41, and thence through the supervisory relay armature 42 and the ground or common connections 43 and 20 to said battery. The flow of'current through this local circuit causes the supervisory lamp 39 to glow, indicating that the called subscriber has not answered the call. It will alsobe seen that the insert-ion of the calling plug in the trunk jack completes a circuit from the battery 44, at exchange D, through the conductor 45 and the coil 4G of the supervisory relay, thence through conductor 47 and line conductor 4S, through the resistance 49 and the jack spring 50, through the contactpoint 51, and thence through the ground or common connections 52 and 53 to said battery. This energizes the relay 46, causing it to attract its armature. In addition to this, vthe insertion of the trunk plug n the jack connected with the line at substation B completes a circuit from the battery 44, through the conductor 54, and coil ot the supervisory relay 55, through the conductor 56, through contact-point 57 and spring 58, thence through conductor 59 and contactpoint 60, through the spring 61 of the ringing-key, thence through the cord-strand 62 and the plug sleeve 63, through the jack sleeve or testing ring 64, thence through conductors 65 and 66, and through impedance coil 67 and conductor 68 to said battery. The current flowing through this cir cuit energizes the relay 55, causing it to attract its armature.

Now when the subscriber at substation Bi answers the call by removing the receiver from the hook-switch, a line circuit. is coinpleted from the battery 44, through conductor 69 and impedance coil 70, thence through the coil of line relay 71, through the liinb or line conductor 72 and the transmitter 73, thence through the hook-switch 74 and the contact-point 75, through the primary 76 of the induction coil, through the other limb or line conductor 77, and thence through the conductor 66 and impedance coil 67, and through the conductor 68 to the said battery. lt will also be seen that with the plug of the trunking cord-circuit in the jack, current is shunted around the relay 71, the shunt connection including the springs 78 and 79 of the jack, and the tip and ring contacts 80 and 81 of the plug, and also the coil of the supervisory relay 82. This supervisory relay, as in the case of the supervisory relays 21, is of relatively low resistance, so as to shunt current around the relay 71, as explained. The energizing of this relay 82 causes it to attract its armature. The

said armature moving toward the magnet completes a trunking line circuit from the battery 44, through the conductors 83 and 84, thence through the arniature 8-5, and contact-point 86, through the conductor 87 and the resistance 88, thence through the cord-strand 89, through the trunking line conductor 90 and the tip spring 91 of the t-runking jack, through the tip 92 of the calling plug at exchange C, thence through, the coil of supervisory relay 93, through the ring contact 94 of said plug, thence through the jack spring 95, through resistance 96, and through the ground con.- nections 97 and 53 to said battery. The flow of current through this grounded trunking line circuitenergizes the relay 93, causing it to attract its armature 42. This, it will be seen, breaks the circuit of the lamp 39, caus ing the latter to stop glowing. Thus, as previously stated, the subscriber at subst-ation B in answering a call extinguishes the supervisory lamp 39. Consequently, the originating operator, as also stated, is in a position to be advised as to when the subscribers answer calls, and has practically complete control of all connections. Both receivers being off the hooks at the substations, the two subscribers are now connected up for talking purposes. lt will be understood that the talking circuit between the two substations includes the substation lines and the trunking line, and also includes the tip and sleeve contacts of the jacks and plugs, and also the talking strands of the cord-circuits. lt will be observed that the condensers 98 and 99 are preferably located in the talking strands of the trunking cord-circuits, and that a condenser 100 is preferably located in the upper talking strand of the originating operators cord-circuit. In this way, current is supplied from central stations out over the lines to the transmitters at the substations, so as to enable the subscribers to carry on conversation, and, furthermore, current is supplied from these batteries in various direc tions for operating the'various signals. The various retardation or impedance coils and the resistance coils and the coils of the relays can be regulated or adjusted, it will be understood, in any suitable manner with re spect to resistance, by those skilled in the art, and in accordance with varying conditions. When the subscriber at substation A hangs up the receiver, the line circuit of this substation is broken, and consequently the supervisory relay 2l is denergized. The armature of this relay, when released, coinpletes a local circuit from the battery 8, through armature 36 and contact point 37, thence through the conductor 38, through supervisory lamp 101, thence through the contact-point 102 and the armature 103, and thence through the ground or connnon connections 104 and 20. The flow of current through this local circuit causes the supervisory lamp 101 to glow. The signal thus displayed advises the originating operator that the calling subscriber has signaled for disconnection. In a similar manner, when the subscriber at substation B hangs up the receiver, the line circuit ot this substation is broken, and consequently the supervisory relay 82 is denergized. rlfhe armature of this supervisory relay, when released, opens up or breaks the aforedescribed grounded trunking line circuit, and this in turn denergizes the relay 93. The armature 42 of this relay when released closes the aforedescribed cir cuit through the lamp 39, thereby giving the originating operator the signal to withdraw the calling plug from the trunking line jack. When ,the originating operator withdraws both plugs of the cord-circuitroin the two jacks, the withdrawal of the calling plug breaks the previously described grounded circuit through the supervisory relay 46, which is associated with the trunking cordcircuit at exchange D. The arinature of this relay when released completes a local circuit from the battery 44, through conductors 83 and S4, thence through the armature 85 and the contact point 105, through the conductor 106, through the lamp 107, thence through the contact point 108 and the armature 109, through the contact point 110 and armature 111, and thence through the connections 112 and 53 to said battery. The flow of current through this .circuit causes the lamp 107 to glow, and the signal thus displayed advises the trunking operator that the originating operator has signaled :tor disconnection and that the plug of the trunking cord-circuit may be withdrawn from the jack of the line leading to the substation B. Thus the trunling operator acts entirely on the instructions given by the originating operator. The circuit arrangement t-hus provided atords a simple and economical method of carrying on trunlring between two common battery or central energy exchanges.

When the subscribers are connected up, it will be seen that the current from the batteries is supplied directly to the lines, rather than through the cord-circuit strands, and that when the plugs of the cord-circuits are in the jacks the only battery current liowng through the cord-circuits is the small amount of line current necessary to energize the supervisory relays 21, 93 and 82. Practically, therefore, there is no direct battery connection between the cord-strands and the batteries, the current, regardless oit' the polarity of the batteries, flowing through the line before it passes through the coils of the supervisory relays. In other words, the coils of these supervisory relays are adapted to lbe placed in the line, so as to serve as line shunts for shunting out the line relays. In this way I provide suitable tiunlring connections and adapt them for use in connection with cord-circuits and signaling circuits which operate in a way to make it unnecessary to supply excessive battery current to the lines through the talking strands of the cord-circuit. This, it will be seen, increases the life of the cord-strands, inasmuch as there is very little liability of their burning out.

That I claim as my invention is- 1. In a trunking telephone system, the combination of an originating operators cord-circuit at one exchange, a calling subscribers line connected with said exchange, a line relay in said calling subscribers line, a supervisory relay in the originating operators cord-circuit adapted to be placed in the line to short-circuit said relay, a supervisory signal controlled by said supervisory relay, a trunling operators cord-circuit located at another exchange, a trunk line extending between the two exchanges, said trunk line terminating in a spring jack at the originating operators exchange and having permanent connection with the trunlring operators cord-circuit at the other exchange, a supervisory relay associated with the originating operators cord-circuit and adapted to be included in a grounded circuit including one limb of the said trunk line, a called subscribers line connected with the trunking operators exchange, a line relay associated with the called subscribers line, a supervisory relay associated with the trunking operators cord-circuit and adapted to be placed in the called subscribers line to short-circuit the line relay, a supervisory lamp controlled by the said supervisory relay which is adapted to be placed in the grounded trunk line circuit, and a normally open switch-point located in the said grounded trunk line circuit and controlled by the said supervisory relay associated with the trunking operators cordcircuit.

2. In a trunking telephone system, the combination of an operators cord-circuit at one exchange, a calling subscribers line connected with said exchange, a trunking operators cord-circuit located at another exchange, a trunk line extending between the two exchanges, an electro-inagnet associated with the originating operators cord-circuit,

a grounded circuit including said electroV magnet and one limb of the said trunk line, a clearing-out or supervisory signal controlled or operated by said electro-magnet,

a called subscribers line connected with the trunking operators exchange, a line relay associated with the called subscribers line, a supervisory relay associated with the trunking operators cord-circuit and adapted to be placed in the called subscribers line to short-circuit said line relay, and a normally open switch-point in said grounded line circuit controlled by said supervisory relay.

3. The combination of a calling sub-v scribers line terminating in a spring jack, a trunk line terminating in a spring jack at the same exchange, an originating operators cord-circuit provided with answering and calling plugs adapted for insertion in said jacks, a line signal associated with the calling subscribers line, a shunt in the cordcircuit adapted to be placed in the calling subscribers line to short-circuit said line signal, an electro-magnet connected with the said calling plug and adapted to be placed in a grounded circuit including one limb of said trunk line, a supervisory lamp controlled by said electro-magnet, a supplemental supervisory relay for controlling a normally open switch-point in the circuit of said supervisory lamp, a trunking operators cordscircuit connected with the trunk line at another exchange, a called subscribe ers line terminating in a jack at the trunking operators exchange, a line signal associated with the called subscribers line, a supervisory relay associated with the trunking operators cord-circuit and adapted to be placed in the called subscribers line to restore the line signal, a normally open switch-point in the said grounded trunk line circuit controlled by said supervisory relay in the trunking operators cord-circuit, a supervisory lamp associated with the trunking operators cord circuit, a local circuit for said supervisory lamp having two normally closed switch-points, one switchpoint being controlled by the said supervisory relay in the trunking operators cordcircuit, another supervisory relay for controlling said other normally closed switchpoint, a normally open switch-point in the circuit of the trunking operators supervisory lamp, and another relay for controlling said normally open switch-point.

t. In a trunlring telephone system, the combination of a calling subscribers line, an originating operators cord-circuit, two supervisory lamps associated with said originating operators cord-circuit, two normally closed switch-points in the circuits of said supervisory lamps, supervisory relays Jfor controlling said normally closed switchpoints, a normally open switch-point in the circuits of said supervisory lamps, another relay for controlling the said normally open switch-point, a trunling operators cordcircuit at another exchange, a trunk line between the two exchanges, a supervisory lamp associated with said trunking operators cord-circuit, two normally closed switch-points in the local circuit of the trunlring operators supervisory lamp, two relays :for controlling said normally closed switch-points, a normally open switch-point in the circuit of the trunking operators supervisory lamp, another relay for controlling said normally open switch-point, a called subscribers line connected with the trunking operators exchange, and a line signal associated with each subscribers line, one of the supervisory relays in each cordcircuit being connected and arranged to be placed in the line to restore the line signal associated therewith.

5. In a trunlring circuit the combination of an originating operators supervisory relay, a supervisory lamp controlled by said supervisory relay, a trunk line, a trunking operators supervisory relay, a normally open switchpoint controlled by said trunking operators supervisory relay, a grounded trunking line circuit including said normally open switchpoint and said originating operators supervisory relay, a trunking operators supervisory lamp, and a normally closed switchpoint in the circuit of said lamp controlled by said trunking operators supervisory relay.

6. In a trunking telephone system, the

combination of a trunk line terminating at one end in a trunking jack, an originating operators cord-circuit provided with a plug adapted for insertion in said ack, a trunking operators cord-circuit connected with the other end of said line, a grounded trunk line circuit including normally open contacts adapted to be closed by the insertion oi said plug in said jack, a trunking operators supervisory relay included in said grounded trunk line circuit, a battery associated with the trunking operators cordcircuit and forming a part of said grounded line circuit, and a supervisory lamp located in a local circuit having a normally closed switch-point controlled by said supervisory relay, the said lamp being caused to glow when the originating operator breaks the said grounded line circuit by withdrawing the plug from the trunking jack.

7. In a telephone system, and in conjunction with calling and called subscribers telephone sets connected with different exchanges, and adapted to be connected through the medium of a trunking line extending between the two exchanges, or between the two divisions of the same exchange, the combination of an operators cord-circuit, spring jacks adapted to receive the plugs of said cord-circuit, lines connected `with said jacks, two supervisory lamps associated with said cord-circuits, normally closed switch-points in the circuits of said lamps controlled by two supervisory relays, a normally open switch-point in the circuits of said supervisory lamps, a third or supplemental relay for controlling said normally open switch-point, a normally open local circuit including said third relay, and also including normally open contacts in one of said jacks, said contacts being closed when the plug is inserted, and a battery included in the local circuit with the relay and normally open contacts.

8. In a trunking telephone system, the combination of a calling subscribers line, an originating operators cord-circuit, a battery associated with said cord-circuit and permanently connected with said line, a trunlring operators cord-circuit, a called subscribers line, a battery associated with the trunlring operators cord-circuit and permanently connected with said called subscribers line, a trunk line permanently connected with the said trunking operators cord-circuit and terminating at the other end in a trunlring ack adapted to receive one of the plugs of the said originating operators cord-circuit, subscribers microphone transmitters receiving current from said batteries, andsuitable line and supervisory signal apparatus also operated by current from said batteries.

9. In a trunlring telephone system, the

combination of a called subscribers line, a

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line relay associated with the line, a trunking operators cord-circuit, a supervisory relay associated with said cord-circuit 'and adapted to be placed in the line to short* circuit said line relay, an originating operators supervisory relay and cord-circuit, a trunk line between the two cord-circuits, a battery connected and arranged to energize the supervisory relay in the trunking operators cord-circuit when the called subscribers line is closed, and a battery and suitable connections whereby the originating operators supervisory relay is denergized when the called subscribers line is opened and the trunking operators supervisory relay thereby denergi-zed.

10. In a trunking telephone system, the combination of subscribers lines, line relays, originating and trunking operators cordcircuits provided with shunts adapted to be placed in the line to short-circuit said line relays, a trunk line between the two cordcircuits, supervisory relays located in said shunts, a supervisory signal associated with the originating operators cord-circuit, and means including electro-magnetic means whereby said signal is displayed or brought int-o action when the supervisory relay associated with the trunking operators cordcircuit is denergized.

ll. In a trunking telephone system, the combination of a trunk line terminating at one end in a jack and connected at the other end with a trunking operators cordcircuit, an originating operators cord-circuit pro vided with a plug adapted for insertion in said jack, a supervisory signal associated with the trunking operators cord-eircuit,

means for supplying current, a called subscribers line, a line relay associated with said called subscribers line, a supervisory relay associated with the trunking opera-1 tors cord-circuit and adapted to be placed in the line to short-circuit said line relay, and a relay and suitable connections whereby said supervisory lamp is caused to glow when the originating operator withdraws the plug` from said ack.

l2. In a trunking telephone system, the combination of suitable switchboard apparatus located at two different exchanges, substations inetallically connected with said exchanges, a trunk line extending between t-he two exchanges, an operators order lline extending between t-he two exchanges, an inductive connection in said order line, an originating operators talking set normally disconnected from the order line, a trunking operators talking set having the receiver thereof permanently connected with said order line, and a normally open key-switch in said order line, controlled by the origi-l nating operator, a central source of current for furnishing talking current to one operators set and the subscribers line of one exchange, and another source for furnishing talking current to the other set and the lines of the other exchange.

13. In a trunking telephone system, the combination of an originating operators cordcircuit located at one exchange, a subst-ation connected with said exchange, a trunking operators cord-circuit located at another exchange, a substation connected with said second exchange, a metallic trunk line terminating in a jack at the originating operators exchange and connected permanently with the t-runking operators cord-circuit at the other exchange, head telephones or talking sets for the said operators at the different exchanges, a two-wire order line extending between the two exchanges, said order line being normally disconnected from the originating operators talking set and permanently connected with the trunking operators head telephone, and 'a normally open keyswitch in said order line, a central source of current for furnishing talking current to one operators set and the subscribers line of one exchange, and another source for furnishing talking current to the other set and the lines of the other exchange.

14. In a trunking telephone system, the combination of one exchange provided with an originating operators cord-circuit, a substation connected with said exchange, a line relay associated with the line of said substation, a line signal controlled by said line relay, a shunt in said originating operators cord-circuit adapted to be placed in the line operators cord-circuit at another exchange, a trunk line between the two exchanges, a substation suitably connected with said second exchange, another line relay associated with the line of said second substation, a shunt in the trunking operators cord-circuit adapted to be placed in the line to short-circuit said second line relay, a line signal controlled by the latter, and energizing circuits for said line relays, each energizing circuit including both sides of the line, said 4shunts normally disconnected at each end-thereof.

l5. In a telephone system, a trunk line, means for grounding one side thereof, when connection is made therewith, two supervisory relays, a circuit for energizing one relay over one side only of said trunk line to ground, a circuit for energizing the other relay over a portion of the same side of the trunk circuit to ground, said relays located at different stat-ions, and signaling means controlled by said relays.

16. Iii a telephone-system, a trunk circuit, means for supplying current, two relays each totally disconnected from the means of current supply, an energizing circuit for one relay controlled by the other and including one side of the trunk circuit, and signaling 'means controlled by Vsaid relays.

Aioo to short-circuit said line relay, a trunking.

17. In a telephone system, two relays, one connected from the trunk line and the cen- 10 controlling the other, a line signal device tral source of current. shunted by the coil of the one relay, and a Signed by Ine at Chicago, Cook county, supervisory signal controlled by the other Illinois, this ith day of April 1902. relay;

18. In a telephone system, a trunk line, ALFRED H' DYSON means for controlling a relay over said Witnesses: trunk line, said relay having both terminals ARTHUR F. DURAND, of the Winding thereof normally totally disl HARRY BAUMGARTNER.

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